The present disclosure relates to a driving method of an image display device.
In recent years, for example, with image display devices such as color liquid crystal display devices and so forth, increase in power consumption along with high performance thereof has become an issue. In particular, along with increased fineness, greater color reproduction range, and increased luminance, power consumption of backlight increases with color liquid crystal display devices for example. In order to solve this problem, a technique has drawn attention wherein in addition to three sub-pixels of a red display sub-pixel for displaying red, a green display sub-pixel for displaying green, and a blue display sub-pixel for displaying blue, for example, a white display sub-pixel for displaying white is added to make up a four-sub-pixel configuration, thereby improving luminance by this white display sub-pixel. High luminance is obtained with the same power consumption as with the related art by the four-sub-pixel configuration, and accordingly, power consumption of backlight can be decreased in the event of employing the same luminance as with the related art, and improvement in display quality can be realized.
Now, for example, a color image display device disclosed in Japanese Patent No. 3167026 includes a unit configured to generate three types of color signals by the three primary additive color method from an input signal, and a unit configured to generate an auxiliary signal obtained by adding each of the color signals of these three hues with the same ratio, and to supply the display signals in total of four types of the auxiliary signal, and the three types of color signals obtained by subtracting the auxiliary signal from the signals of the three hues to a display device. Note that, according to the three types of color signals, the red display sub-pixel, green display sub-pixel, and blue display sub-pixel are driven, and the white display sub-pixel is driven by the auxiliary signal.
Also, with Japanese Patent No. 3805150, there has been disclosed a liquid crystal display device capable of color display having a liquid crystal panel with a sub-pixel for red output, a sub-pixel for green output, a sub-pixel for blue output, and a sub-pixel for luminance serving as one principal pixel unit, including an arithmetic unit configured to obtain a digital value W for driving the sub-pixel for luminance using digital values Ri, Gi, and Bi of the sub-pixel for red input, sub-pixel for green input, sub-pixel for blue input, and sub-pixel for luminance obtained from the input image signal, and digital values Ro, Go, and Bo for driving the sub-pixel for red output, sub-pixel for green output, sub-pixel for blue output, and sub-pixel for luminance, the arithmetic unit obtains each value of the Ro, Go, Bo, and W so as to satisfy the following relationship,Ri:Gi:Bi=(Ro+W):(Go+W):(Bo+W)and also so as to enhance luminance by addition of the sub-pixel for luminance as compared to a configuration made up of only the sub-pixel for red input, sub-pixel for green input, and sub-pixel for blue input.
Further, with PCT/KR2004/000659, there has been disclosed a liquid crystal display device configured of a first pixel made up of a red display sub-pixel, a green display sub-pixel, and a blue display sub-pixel, and a second pixel made up of a red display sub-pixel, a green display sub-pixel, and a white display sub-pixel, a first pixel and a second pixel are alternately arrayed in a first direction, and also arrayed in a second direction, or alternatively, there has been disclosed a liquid crystal display device wherein a first pixel and a second pixel are alternately arrayed in the first direction, and also in a second direction a first pixel is adjacently arrayed, and moreover, a second pixel is adjacently arrayed.
In the event that external light irradiates an image display device, or in a back lit state (under a bright environment), visibility of an image displayed on the image display device deteriorates. Examples of a method for handling such a phenomenon include a method for changing a tone curve (γ curve). For example, if description will be made with a tone curve as a reference, in the event that output gradation as to input gradation when there is no influence of external light has a relation such as a straight line “A” shown in FIG. 26A, output gradation as to input gradation when there is influence of external light is changed to a relation shown in a curve “B” in FIG. 26A. If this will be described with a γ curve as a reference, in the event that output luminance as to input gradation when there is no influence of external light has a relation such as a curve “A” (γ=2.2) shown in FIG. 26B, output luminance as to input gradation when there is influence of external light is changed to a relation shown in a curve “B” in FIG. 26B. Usually, such change is performed as to each of a red display sub-pixel, a green display sub-pixel, and a blue display sub-pixel making up each pixel.